In the 3GPP (3rd Generation Partnership Project) specification TS 23.041, a CBS (Cell Broadcast Service) is defined, which is similar to the Teletex service offered on television, in that like Teletex, it permits a number of unacknowledged general CBS messages to be broadcast to all receivers within a particular region. CBS messages are broadcast to defined geographical areas known as cell broadcast areas. These areas may comprise of one or more cells, or may comprise the entire cellular network. Individual CBS messages will be assigned their own geographical coverage areas by a mutual agreement between the information provider and the network operator. CBS messages may originate from a number of Cell. Broadcast Entities (CBEs), which are connected to a Cell Broadcast Centre (CBC). CBS messages are then sent from the CBC to the cells, in accordance with the CBS's coverage requirements.
The work to standardize multicast transmission as a new service has been started in 3GPP. The aim is to enhance the current capabilities not only in UTRAN but also in core networks, so as to provide a service using common network resources and being provided only to a restricted group of people in a cell. These requirements are not yet fulfilled in the above described cell broadcast concept.
Basically the standardisation of the multicast type of service means that the new service concept should be capable of transmitting data simultaneously to a group of people, who previously indicated their interest to receive data belonging to a multicast service. Thus, when the multicast related data is transmitted from the core network to the UTRAN, this data is not addressed to only one user equipment (UE), but to a group of UEs which may even be located in different cells.
However, the known CBS is designed for transmission of cell broadcast messages, which in practice means that all UEs, which are in the cell, are allowed to received the transmitted data. Therefore, the functionality of the CBC doesn't provide any solution e.g. how different UEs in a multicast group can be identified and how the evaluation between the cells (e.g. the number of UEs in the cell, the load of the cell etc.) and between the different sessions (e.g. delay requirements for the transmission, priority of the session etc) can be taken care of.